Biochemical effects of pollutant exposure in fish from urban creeks in Greenville, SC (USA)

The city of Greenville, SC is a rapidly expanding urban area located on the Reedy River in the upstate of South Carolina. Historical and current point-source pollutants and runoff from impermeable surfaces have resulted in a contaminated river environment, which through previous studies was demonstrated to be reflected in biological effects in fish species in the river. Because it was not known how much smaller tributaries in the urbanized area were contributing to the pollution of the main stem of the Reedy River, we collected fish (bluehead chub (Nocomis leptocephalus), creek chub (Semotilus atromaculatus), bluegill (Lepomis macrochirus), and redbreast sunfish (Lepomis auritus)) from five smaller urban creeks in the Greenville area and measured several biomarkers of exposure in these animals. Enzymatic activities of cytochrome P450-1A (CYP1A) and glutathione S-transferase (GST) were measured, and bile samples were analyzed for fluorescence caused by polynuclear aromatic hydrocarbons (PAHs) and for excreted estrogenic compounds. The results show that some creeks triggered significant biomarker responses in collected fish, while others were relatively clean. In particular, PAHs appear to be prevalent and caused biochemical effects, while estrogenic compounds were not significantly increased in the bile of fish from these urban creeks. A striking observation was the difference in enzyme activities in chub species compared to sunfish species; sunfish had up to five times higher CYP1A activities than chubs, while the chubs had significantly higher GST activity than sunfish. These species differences should be taken into account when they are incorporated in environmental risk assessment and biological effect monitoring programs

A new method for computing a column reduced polynomial matrix

A new algorithm is presented for computing a column reduced form of a given full column rank polynomial matrix. The method is based on reformulating the problem as a problem of constructing a minimal basis for the right nullspace of a polynomial matrix closely related to the original one. The latter problem can easily be solved in a numerically reliable way. Two examples illustrating the method are included. Keywords: Polynomial matrix, column reduced, minimal polynomial basis, numerical method

Modeled contrast in the response of the surface energy balance to heat waves for forest and grassland

Observations have shown that differences in surface energy fluxes over grasslands and forests are amplified during heat waves. The role of land-atmosphere feedbacks in this process is still uncertain. In this study, a single-column model (SCM) is used to investigate the difference between forest and grassland in their energy response to heat waves. Three simulations for the period 2005-11 were carried out: a control run using vegetation characteristics for Cabauw (the Netherlands), a run where the vegetation is changed to 100% forest, and a run with 100% short grass as vegetation. A surface evaporation tendency equation is used to analyze the impact of the land-atmosphere feedbacks on evapotranspiration and sensible heat release under normal summer and heat wave conditions with excessive shortwave radiation. Land-atmosphere feedbacks modify the contrast in surface energy fluxes between forest and grass, particularly during heat wave conditions. The surface resistance feedback has the largest positive impact, while boundary layer feedbacks generally tend to reduce the contrast. Overall, forests give higher air temperatures and drier atmospheres during heat waves. In offline land surface model simulations, the difference between forest and grassland during heat waves cannot be diagnosed adequately owing to the absence of boundary layer feedbacks

Phylogenetic signals in detoxification pathways in Cyprinid and Centrarchid species in relation to sensitivity to environmental pollutants

Observations in a previous study on biomarker responses in fish collected from urban creeks in Greenville, SC, indicated that there might be considerable differences in the expression of biotransformation enzymes in chub and sunfish species. To further investigate these species differences a dosing experiment was performed in which bluehead and creek chub (Nocomis leptocephalus and Semotilus atromaculatus), and redbreast sunfish, pumpkinseed, and bluegill (Lepomis auritus, L. gibbosus, and L. macrochirus) were injected with benzo[a]pyrene (BaP) as a model compound for common pollutants in urban creeks. Fish were injected with BaP doses of 0, 25 and 50 mg/kg, and after 3 days BaP metabolites in bile, and enzymatic activities of cytochrome P450-1A (CYP1A), UDP-glucuronosyltransferase (UGT) and glutathione S-transferase (GST) were measured. CYP1A activity was significantly increased after BaP dosing in both species groups, but chubs had significantly lower levels than were observed in the dosed sunfish. The UGT activity in unexposed animals was comparable in both species groups, and significantly increased in both groups as a result of BaP dosage. Finally, GST activity was significantly higher in chubs, but did not change in either species group as a result of BaP exposure. There were no significant differences between species within each species group, and the results confirmed that unexposed chubs have much lower CYP1A activity, but a much higher GST activity than unexposed sunfish. The metabolized BaP was excreted in both species groups, but at the time of sampling there were no differences in the amount of BaP metabolites in the bile of dosed animals. The differences in baseline enzyme activity and induction capacity between both species groups are an example of phylogenetically determined differences between fish families, and may explain why chubs are in general more sensitive to exposure to environmental pollutants than sunfish. This conclusion was corroborated by the observation that the highest BaP dose of 50 mg/kg was close to the apparent LC50 for chub, while no mortality was observed in the sunfish at this dose

Future extreme precipitation intensities based on a historic event

In a warmer climate, it is expected that precipitation intensities will increase, and form a considerable risk of high-impact precipitation extremes. This study applies three methods to transform a historic extreme precipitation event in the Netherlands to a similar event in a future warmer climate, thus compiling a future weather scenario. The first method uses an observation-based non-linear relation between the hourly-observed summer precipitation and the antecedent dew-point temperature (the Pi–Td relation). The second method simulates the same event by using the convective-permitting numerical weather model (NWP) model HARMONIE, for both present-day and future warmer conditions. The third method is similar to the first method, but applies a simple linear delta transformation to the historic data by using indicators from The Royal Netherlands Meteorological Institute (KNMI)'14 climate scenarios. A comparison of the three methods shows comparable intensity changes, ranging from below the Clausius–Clapeyron (CC) scaling to a 3 times CC increase per degree of warming. In the NWP model, the position of the events is somewhat different; due to small wind and convection changes, the intensity changes somewhat differ with time, but the total spatial area covered by heavy precipitation does not change with the temperature increase. The Pi–Td method is simple and time efficient compared to numerical models. The outcome can be used directly for hydrological and climatological studies and for impact analysis, such as flood-risk assessments.</p

Экспериментальный анализ фонетических изменений в английской речи датско-английских билингвов

Одним из ключевых показателей, присущих двуязычному речевому поведению молодых датчан, является специфическая маркированность их английского произношения, что обращает на себя внимание уже с первых минут общения с ними. Эта маркированность произношения проявляется как следствие фонологической интерференции, которая возникает под влиянием артикуляции, интонации, ритмики, ударения первого (датского) языка на соответствующие параметры произношения второго (английского) языка.Одним з ключових показників, властивих двомовній мовній поведінці молодих данців, є специфічна маркированість їх англійської вимови, що звертає на себе увагу вже з перших хвилин спілкування з ними. Ця маркированість вимови виявляється як наслідок фонологічної інтерференції, яка виникає під впливом артикуляції, інтонації, ритміки, наголосу першої (данської) мови на відповідні параметри вимови другої (англійської) мови

Релігійний чинник у процесі вдосконалення Конституції України

Multiple states of woody cover under similar climate conditions are found in both conceptual models and observations. Due to the limitation of the observed woody cover data set, it is unclear whether the observed bimodality is caused by the presence of multiple stable states or is due to dynamic growth processes of vegetation. In this study, we combine a woody cover data set with an above ground biomass data set to investigate the simultaneous occurrences of savanna and forest states under different precipitation forcing. To interpret the results we use a recently developed vegetation dynamics model (the Balanced Optimality Structure Vegetation Model), in which the effect of fires is included. Our results show that bimodality also exists in above ground biomass and retrieved vegetation structure. In addition, the observed savanna distribution can be understood as derived from a stable state and a slightly drifting (transient) state, the latter having the potential to shift to the forest state. Finally, the results indicate that vegetation structure (horizontal vs. vertical leaf extent) is a crucial component for the existence of bimodality

Does teachers' pedagogical content knowledge affect their fluency instruction?

The relation is studied between teachers' pedagogical content knowledge of reading and the quality of their subsequent classroom behaviour in teaching fluent reading. A confirmatory factor analysis model with two latent variables is tested and shows adequate goodness-of-fit indices. Contrary to our expectations, the results of structural equation modelling reveal a small but significant gamma-value of .29, indicating that only 8% of the variance in teachers' classroom behaviour in teaching fluent reading is accounted for by teachers' pedagogical content knowledge of reading. Presumably teacher knowledge is not as stable and conclusive as one might think. More research is needed in determining the factors that work restricting for teachers in putting their knowledge into classroom practice. It is recommended that preservice and in-service teacher training should not be limited to transfer of knowledge, but should also assist teachers in designing and performing effective fluent reading instruction